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Human Biology Unit 3 + 4 > Endocrine and Nervous System > Flashcards

Endocrine and Nervous System Flashcards

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1
Q

The two parts of the nervous system

A

Central Nervous System

  • Brain and spinal cord
  • Control centre

Peripheral Nervous System

  • Nerve cells, receptors
  • Carry messages to and from CNS
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2
Q

Functional Types of Neurons

A
  1. Sensory
    - carry messages from receptors in sense organs towards CNS
  2. Motor
    - Carry messages away from CNS
  3. Interneuron
    - Link between sensory and motor neurones in the CNS
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3
Q

Structural types of Neurons

A
  1. Multipolar
  2. Bipolar
  3. Unipolar
  4. Pesudounipolar
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4
Q

Conduction along myelinated fibres

A

In unmyelinated fibres, depolarisation of one area of the membrane causes another repolarization immediately next to the original stimulus

This process repeats along the whole membrane, moving away from the original stimulus, from one channel to the next

The nerve impulse is prevented from going backwards by the refractory period

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5
Q

Conduction along myelinated fibres

A

In myelinated fibres, the nerve fibres are insulated from the extracellular fluid by schwann cells
Ions cannot flow where the fibre is insulated so no action potential can occur, except at the nodes of ranvier

Sodium ions will diffuse along axon through the cytoplasm until they reach the next exposed gate (node of ranvier), the action potentials are said to jump from one node to another

With action potentials only occurring at the nodes of ranvier, there is less distance to cover = much faster
Conduction along a myelinated axon is also called saltatory conduction

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6
Q

Synapses

A
  1. Nerve impulse reaches axon terminal which activates voltage-gated ion channels in presynaptic membrane
  2. Calcium ions flow into the presynaptic axon terminal
  3. This stimulates the release of chemicals called neurotransmitters from vesicles by exocytosis at the presynaptic membrane
  4. The neurotransmitters diffuse across the synaptic cleft and attach to receptors on the postsynaptic membrane
  5. This stimulates ligand-gated protein channels to open, which allows an influx of sodium ions into the dendrite, initiating a nerve impulse in the next neuron
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7
Q

Examples of Neurotransmitters

A

→ Acetylcholine → Noradrenaline → Dopamine → Histamine → Serotonin

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8
Q

Removal of Neurotransmitters

A

Diffusion
→ Neurotransmitters exit the synaptic cleft via diffusion as they move from a high to a lower concentration

Enzymes degradation
→ Enzymes can inactivate the neurotransmitter, these are released by the postsynaptic membrane when the neurotransmitter has been received

Active reabsorption
→ Reabsorbed back into the presynaptic axon terminal by active transport

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9
Q

In the intracellular and extracellular fluids the concentrations are:

A

→ Extracellular fluid has a high concentration of sodium ions and chlorine ions

→ Intracellular fluid has a high concentration of potassium ions and various negative ions and low concentrations of sodium and chlorine ions

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10
Q

The cell membrane is:

A

Highly permeable to potassium ions
Slightly permeable to sodium ions
Impermeable to large negative ions

→ Therefore there is a tendency for potassium ions to diffuse out of the cell, this makes the cell more negatively charged as its losing positive ions

The potential difference created is called the membrane potential
The resting membrane potential is the membrane potential/difference of unstimulated nerve cells

> -70 mV (millivolts) - This means the potential of the inside of the membrane is 70mV less than that of outside

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11
Q

Maintaining the potential difference in two ways

A
  1. Sodium potassium pump
    → Cell activity moves sodium ions out of the cell and potassium ions into the cell using sodium and potassium protein pumps, for every 3 sodium ion molecules released, 2 potassium ion molecules will be brought back
  2. Cell membrane is not equally permeable to all ions which means many negatively charged ions are trapped inside the cell
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12
Q

Action Potential

A

When a sufficiently strong stimulus is applied to a nerve fibre, the membrane will become more permeable to sodium ions therefore sodium channels will open and diffuse into cell

→ This enables cell to be more positive inside than the outside and increases the potential difference

If the level of stimulation exceeds 15mV (-70 to -55) it is known as an All or None response and can be passed along axon

→ When it exceeds 15mV it is classified as a sufficiently strong stimulus
→ Doesn’t matter size of impulse, if above 15 it will go if it doesn’t nothing will happen
→ ‘passed along axon’ is known as the action potential

The movement of sodium ions is independent to the strength of the stimulus

The flood of sodium ions into the cell causes the inside of the cell to reach a charge of 0 and slightly positive → Depolarisation/switching of charges

To re-polarize the cell, the sodium channels close and potassium ions diffuse out of cell therefore potassium ions open to return and create a negative charge

When potassium channels remain open for longer what is needed the potential drops lower than the resting → hyperpolarized

The rapid depolarisation and repolarisation is called the action potential
The movement of an action potential along a nerve is known as the nerve impulse

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13
Q

Nervous system divides into two divisions

A

Central nervous system

Peripheral nervous system

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14
Q

Central nervous sytem

A

Brain and spinal cord

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15
Q

Peripheral nervous system

A

Nerves, receptors and effectors

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16
Q

Peripheral nervous system divides into two divisions

A

Afferent: carries into to CNS from receptors

Efferent: carries info away from CNS to effectors

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17
Q

Afferent division

A
  1. Somatic: carry info from receptors in skin, muscles or joints
  2. Visceral: Carry info from receptors in internal organs
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18
Q

Efferent division

A
  1. Somatic: carry info to skeletal muscles

2. Autonomic: Carry info to involuntary muscles and glands

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19
Q

Autonomic divisions

A

Parasympathetic: rest and digest

Sympathetic: fight or flight

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20
Q

What is a receptor

A

Detects changes in the body’s internal or external environment

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21
Q

Thermoreceptors purpose

A

Detect temperatures

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22
Q

Thermoreceptors location

A

Skin - detect external temp

Hypothalamus - detect internal temp

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23
Q

Thermoreceptors function

A

Hypothalamus collects information which can regulated body temperature

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24
Q

Osmoreceptors purpose

A

Detect osmotic pressure

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25
Q

Osmoreceptors location

A

Hypothalamus

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26
Q

Osmoreceptors function

A

Stimulate the posterior pituitary to release ADH to regulate osmotic pressure

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27
Q

Chemoreceptors purpose

A

Detects chemicals

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28
Q

Chemoreceptors location

A

Nose and mouth and internally

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29
Q

Chemoreceptors function

A

Receptors detect composition of body fluids (pH, O2 and CO2) and these messages are sent to the respiratory centre to regulate breathing rate

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30
Q

Touch receptors purpose

A

Detect touch

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31
Q

Touch receptors location

A

mostly in the skin

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32
Q

Touch receptors function

A

Detect light touches and harder touches and these messages are sent to the brain to give response

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33
Q

Pain receptors prupose

A

Detect pain

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34
Q

Pain receptors location

A

Skin and mucous membrane

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35
Q

Pain receptors function

A

Stimulated by damage to tissues, excessive heat or chemicals and messages are sent to brain to detect pain

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36
Q

Describe the Cerebrum

A

Many convolutions which increases surface area

Separated by shallow folds called sucli or deep folds called fissures

Deepest fissure - longitudinal fissure which separates brain into right and left hemisphere

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37
Q

4 lobes of brain

A

Frontal
Temporal
Occipital
Parietal

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38
Q

Frontal lobe

A

Important for voluntary movement, expressive language and for managing higher level executive function

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39
Q

Occipital Lobe

A

The occipital lobe is the visual processing area of the brain. It is associated with visuospatial processing, distance and depth perception, colour determination, object and face recognition, and memory formation

40
Q

Temporal lobe

A

important role in processing affect/emotions, language, and certain aspects of visual perception

41
Q

Parietal lobe

A

Processes sensory information it receives from the outside world, mainly relating to touch, taste, and temperature

42
Q

Cerebral cortex matter

A

Grey

43
Q

Tracts

A

White matter

44
Q

Types of tracts

A

Connect various areas in the same hemisphere

Carry impulses between hemispheres

Connect to other parts of brain or spinal cord

45
Q

Basal ganglia

A

Underneath the tracts, grey matter

46
Q

Functional areas of the brain

A
  1. Sensory areas
  2. Motor areas
  3. Association areas
47
Q

Sensory areas

A

Interpret impulses from receptors, perception of sense

48
Q

Motor areas

A

Control muscular movements, initiation and control of voluntary muscle

49
Q

Association areas

A

Intellectual and emotional processes, involved in activities such as thinking, reasoning, learning, memory

50
Q

Corpus Callosum

A

Wide band of nerve fibres underneath the cerebrum

Enables both hemispheres to communicated

51
Q

Cerebellum Location

A

Back of the cerebrum

52
Q

Role of Cerebellum

A

Receives constant input from the senses

Maintains muscles tone and posture

53
Q

Hypothalamus location

A

Located in middle of brain

54
Q

Hypothalamus function

A

Controls homeostasis
Body temperatures
Autonomic nervous system

55
Q

Medulla Olbongata

A
  1. Cardiac centre - regulated rate and force of heartbeat
  2. Respiratory centre - control of rate and depth of breathing
  3. Vasomotor centre - regulated diameter of blood vessels
56
Q

Protection of CNS - Bone

A

Hardness of the cranium encases the brain

57
Q

Protection of CNS - Meninges

A
  1. Dura mater - tough fibrous, prevents brain from moving around
  2. Arachnoid mater - loose mesh fibres
  3. Pia mater - creates a seal that protect brain from infection
58
Q

Cerebrospinal fluid properties

A

Clear watery fluid, contains glucose, protein, urea and salta

59
Q

Functions of cerebrospinal fluid

A

Protection - shock absorber

Support - brain is suspended in cranium

Transport - takes nutrients to cells and wastes away

60
Q

Reflex

A

Triggered by a stimulus
Involuntary
Rapid
Stereotypes

61
Q

Reflex arc

A
  1. Receptor in the end of a sensory neuron detect a change in the environment and reacts to this stimulus by producing a nerve impulse
  2. Sensory neuron carries impulse to spinal cord
  3. Information is processed in CNS, nerve impulse is passed across a synapse to a motor neuron via an interneuron
  4. Motor neuron then carries nerve impulse to an effector
  5. The effector receives nerve impulse and carries out an appropriate response
62
Q

Protective reflexes

A

Blinking
Sneezing
Coughing

63
Q

Exocrine Glands

A

Secrete into a duct that carries the secretion to the body surface

64
Q

Endocrine glands

A

Secrete hormones into the extracellular fluid that surrounds the cells making up the gland

65
Q

Pituitary gland

A

Lies just underneath the hypothalamus and is joined by the stalk called the infundibulum

Has two lobes

66
Q

Anterior lobe

A

Connected to the hypothalamus via blood vessels

Produces own hormones

Releases hormones via chemical stimulation

67
Q

Posterior lobe

A

Connected to hypothalamus by nerve fibres

Releases hormones from hypothalamus

Releases hormones via nervous stimulation

68
Q

Transmission of hormones from the posterior lobe

A
  1. Hormones transport down the axons of the nerve cells to the posterior lobe
  2. There are stored in the posterior lobe until required
  3. Their release is triggered by a nervous impulse which is initiated by the hypothalamus and conducted along the nerve cell extensions
69
Q

Hormones

A

Change functioning of cells by changing the type, activities or quantities of proteins produced

70
Q

Hormones Functions

A

Activate certain genes so that a particular enzyme or protein produced

Change the shape or structure of an enzyme

Change the rate of production of an enzyme or protein

71
Q

Protein and Amine hormones

A
  1. Attach to receptors on surface of cell membrane of target cell
  2. This combination of hormone and receptor causes a secondary messenger to diffuse through the cell and activate particular enzymes within the cytoplasm
  3. Faster acting hormones
72
Q

Steroid hormones

A
  1. Enter target cells and combine with receptor protein inside the cytoplasm of cell
  2. Lipid soluble so easily diffuse through cell membrane
  3. The hormone-receptor complex then enters the nucleus and activates genes controlling formation of particular proteins
  4. Slower acting hormones
73
Q

Anterior lobe Hormones

A
  1. Follicle Stimulating Hormone: Ovaries and testes : growth of follicles, production of sperm
  2. Luteinising hormone: ovaries and testes: ovulation and maintenance or corpus luteum and secretion of testosterone
  3. Growth hormone: all cells: growth and protein synthesis
  4. Thyroid-stimulating hormone: thyroid gland: secretion of hormones from the thyroid
  5. Adrenocorticotropic hormone: adrenal cortex: secretion of hormones from the adrenal cortex
  6. Prolactin: mammary glands: milk production
74
Q

Posterior lobe

A

Antidiuretic hormone

  1. Kidneys: reabsorption
  2. Uterus: contractions of uterus during childbirth

Oxytocin
1. Mammary glands: release of milk

75
Q

Thyroid

A

Thryoxine: Most body cells, increases metabolic rate, oxygen consumption and heat production

Calcitonin: bones, kidneys, decreases calcium and phosphate in the blood

76
Q

Parathyroid

A

Parathyroid: bones and kidneys, increases level of calcium in blood

77
Q

Thymus

A

Thymosis: T-lymphocytes, stimulates development and maturation of t-lymphotcytes

78
Q

Adrenal cortex

A
  1. Corticosteroids: kidneys, increases reabsorption of sodium ions and excretion of potassium ions
  2. Cortisol: most body cells, promotes normal metabolism, helps body deal with stress, promotes damages tissues
79
Q

Adrenal medulla

A

Adrenaline: most body tissues, prepares the body for fight or flight response

80
Q

Pancreas

A

Insulin: most body cells, stimulates uptake of glucose, lowers blood glucose level

Glucagon: liver, stimulates breakdown of glycogen and fat

81
Q

Testes

A

Androgens: many tissues, stimulate sperm production, growth of skeleton, development of male sexual characteristics

82
Q

Ovaries

A

Oestrogen: many tissues, stimulate development of female sexual characteristics

Progesterone: uterus and mammary glands, regulates menstural cycle and pregnancy

83
Q

Homeostasis

A

Maintenance of internal environment

84
Q

Feedback system

A

The response causes the stimulus a direction opposite to that of the original stimulus

85
Q

What does a feedback system consists of

A
  1. Stimulus
  2. Receptor
  3. Modulator
  4. Effector
  5. Feedback
86
Q

Positive feedback

A

The response to stimulus reinforcer and intensifies the stimulus

87
Q

Heat Gain Internal

A

Heat is a by-product of cellular respiration

Metabolic rate, which energy is released by the breakdown of food

Metabolic rate is affected by exercise, stress and body temperature

88
Q

Heat Gain External

A

Radiation or conduction from surroundings

89
Q

Heat Loss Internal

A

Evaporation of water from skin and lungs

Warm air breathed out

Warm urine and faeces

90
Q

heat Loss External

A

Radiation

Conduction

Convection to surroundings

91
Q

Conduction

A

Transfer of heat via direct contact with another object

Involves the exchange of heat from molecule of higher temperature to molecule of lower temperature when they vibrate and touch

92
Q

Convection

A

Transfer to heat to air around the body

When cool air makes contact with our body it heats up and becomes less dense, less dense air rises and is replaced by cooler more dense air

93
Q

Radiation

A

Transfer to heat without contact

All objects emit heat to their surroundings by radiation

Heat will radiate to cooler objects around you like the floor and walls

94
Q

Evaporation

A

Transfer of heat through evaporation of liquid to gas

Heat energy is required to change from a lower energy liquid phase to a higher energy gas phase

This heat energy is absorbed from the surface of the skin, which then cools when the water evaporates, meaning heat is lost

95
Q

Temperature tolerance

A
  1. Heat stroke, body temp rises by regulatory mechanisms are not working
  2. Heat exhaustion, result of extreme sweating and vasodilation
  3. Hypothermia, if cored body temp balls below 33 degrees
96
Q

Temperature receptors

A
  1. Peripheral thermorecepotors skin and mucous membranes

Human Biology Unit 3 + 4 (7 decks)

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